Relativistic Coulomb sum rules for (e,e').

A Coulomb sum rule is derived for the response of nuclei to (e, e ′) scattering with large three-momentum transfers. Unlike the nonrelativistic formulation, the relativistic Coulomb sum is restricted to spacelike four-momenta for the most direct connection with experiments; an immediate consequence is that excitations involving antinucleons, e.g., N ¯ N pair production, are approximately eliminated from the sum rule. Relativis-tic recoil and Fermi motion of target nucleons are correctly incorporated. The sum rule decomposes into one-and two-body parts, with correlation information in the second. The one-body part requires information on the nucleon momentum distribution function, which is incorporated by a moment expansion method. The sum rule given through the second moment (RCSR-II) is tested in the Fermi gas model, and is shown to be sufficiently accurate for applications to data.